Hmm im looking at your sig a few changes i recommend dump the AMD X2 go for a Q6600 g0 version drop 1 of the harddrives you want drop the 4gb of G.Skill i heard those 2gb sticks suck not really good go for some Crucial Ballistix or corsair XMS2 newegg.com have some pretty good prices.The Q6600 g0 you will have to get somewhere else bacause newegg gives you a random one it could be g0 or b3 i got the g0 though got lucky.

Yeah, you need an Nvidia chipset mobo for SLI, not just 2x PCIe, maybe an EVGA NF680i mobo for intel CPU. have no idea about AMD mobos. If its not time urgent, you could wait for the 780i chipset, and see how they turn out.

depends if you want to spend more. the only conroe chip that is close to the same price as a 6400 is an e6300. no doubt a good chip, but you will have to overclock it pretty heavily to match the performance of the 6400.
you could go allendale, meh...but the same would apply.
q6600 is almost 100 dollars more, but it is a quad core. if you are planning to spend that much on a 6850, i suggest saving 10 bucks and getting a q6600. 6850 is a rockin chip, just kinda expensive when many of the conroe ships will clock that high for less money.
i wouldnt get a 680i. certainly is looking like they are NOT going to support yorkfield quads (new generation from intel due Q1 next year)...they will likely support wolfdale (dual core version of yorkfield).
either a p35 or one of the new chipsets would be advisable for a new build.
AMD mobo would be the new MSI K9A2 platinum (if you can find it) which is an am2+ mobo and will support the AMD quad cores. yes, it will also work with an am2 cpu. i would suggest the x2 5000 black edition, which has an unlocked multiplier and will overclock (probably) to the speed of a 6400...with less heat than a 6400 at stock. i dont know if you can find one in canada, probably so. at newegg it is 130 dollars, 60 cheaper than the 6400.
if you want to not shell out the dough for an am2+ mobo, anything with a 590SLI chipset is great.

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